1. Field of the Invention
The present invention relates to a technology for recording or reproducing information from a recording medium.
2. Description of Related Art
Conventionally, there is known a technology for recording and processing information by using magnetic tape such as a VCR (Video Cassette Recorder).
There is also known a technology for recording information on disk-shaped information recording media such as a CD-RW (Compact Disc—ReWritable) and a DVD-RAM (Digital Versatile Disc—Random Access Memory) instead of on the magnetic tape.
The VCR records information sequentially on magnetic tape. Since intended information also needs to be reproduced sequentially, an information access speed is slow. By contrast, when information is recorded on disk-shaped information recording media such as CD-RW and DVD-RAM, they can provide a so-called random access to reproduce intended information immediately. The CD-RW and the DVD-RAM are characterized by a faster information access speed than the VCR.
In recent years, products on the market include a DVD recorder that digitally records videos captured through TV broadcasting and line input on a write-once DVD. The DVD recorder manages a video recorded on a recording medium based on a management unit called a video title set from the beginning to the end of a single recording operation.
FIG. 1 shows a data structure of a recording medium 101. According to this data structure, video title sets increase for the number of recorded videos such as video title set #1 (102), video title set #2 (103), . . . , and video title set #N (104). At this time, video title set #1 (102), video title set #2 (103), . . ., and video title set #N (104) correspond to title #1 (105), title #2 (106), . . . , and title #N (107) one to one, respectively. Further, each title is subdivided into units like chapter #1 (108), chapter #2 (109), . . . , and chapter #M (110) for management. For example, a chapter is increased each time the recording time exceeds five minutes, FIG. 2 shows a more detailed data structure. The data structure in FIG. 2 is configured on the recording medium 301 according to a finalization process. Information recorded on the recording medium 301 is managed by one video manager 302 and video title set #1 (303), video title set #2 (304), . . . , and video title set #L (305).
The video manager 302 comprises video manager information 306, a video manager menu video object set 307, and a video manager information backup 308. The video manager information 306 is used to manage the entire information recorded on the recording medium 301. The video manager menu video object set 307 is used to display a menu screen for reproducing information recorded on a recording medium 301. The video manager information backup 308 is backup information for the video manager information 306.
Each video title set comprises video title set information 309, a video title set menu video object set 310, a video title set video object set 311, and a video title set information backup 312. The video title set information 309 manages the entire of one video title set. The video title set information 309 is used to manage information in units of titles or chapters as shown in FIG. 1. The video title set menu video object set 310 provides information for reproducing a menu screen used to reproduce information within one video title set. The video title set video object set 311 is an AV stream of the recorded video, i.e., the information itself. The video title set information backup 312 is backup information of video object set information.
The video manager menu video object set 307 and the video title set menu video object set 310 may or may not be configured on the recording medium.
The above-mentioned recording system must create and record information about a video title set each time the recording terminates. Accordingly, a process to terminate the recording becomes time-consuming. Further, there is a limitation on the number of video title sets and titles (up to 99) that can be created on the recording medium. This also limits the number of times of recording operations. As a result, there may be a case where just a half of the recordable capacity is consumed on the recording medium even if the number of operations allowed for recording is reached. Consequently, there is a possibility of ineffectively using recording areas on the recording medium.